U.S. patent application number 16/412782 was filed with the patent office on 2019-08-29 for traveling control apparatus.
The applicant listed for this patent is DENSO CORPORATION, TOYOTA JIDOSHA KABUSHIKI KAISHA. Invention is credited to Naoki KUSUMOTO, Takashi MAEDA, Takuma SUDO, Mitsuhiro TOKIMASA.
Application Number | 20190263402 16/412782 |
Document ID | / |
Family ID | 62146223 |
Filed Date | 2019-08-29 |
United States Patent
Application |
20190263402 |
Kind Code |
A1 |
TOKIMASA; Mitsuhiro ; et
al. |
August 29, 2019 |
TRAVELING CONTROL APPARATUS
Abstract
A traveling control apparatus performs a target-following
control process on a target to be followed detected by a target
detecting unit. Further, the traveling control apparatus calculates
a probability that the target to be followed is within an own lane,
and determines whether a degree of recognition by the target
detecting unit of the target to be followed is in a weakly
recognized state where the degree of recognition is weaker than a
predetermined degree. The apparatus sets a reliability of the
target to be followed on the basis of the probability calculated by
a probability calculating process and a determination result by a
determining process, and controls acceleration of an own vehicle so
that a jerk which is a differential value of the acceleration
becomes smaller as the reliability of the target to be followed is
lower while the target-following control process is performed.
Inventors: |
TOKIMASA; Mitsuhiro;
(Kariya-city, JP) ; SUDO; Takuma; (Kariya-city,
JP) ; MAEDA; Takashi; (Toyota-shi, JP) ;
KUSUMOTO; Naoki; (Toyota-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DENSO CORPORATION
TOYOTA JIDOSHA KABUSHIKI KAISHA |
Kariya-city
Toyota-shi |
|
JP
JP |
|
|
Family ID: |
62146223 |
Appl. No.: |
16/412782 |
Filed: |
May 15, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2017/039082 |
Oct 30, 2017 |
|
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16412782 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60W 30/165 20130101;
B60W 2720/10 20130101; B60W 30/143 20130101; B60W 2720/106
20130101; B60W 30/16 20130101; G05D 2201/0213 20130101; B60W
50/0098 20130101; B60K 2031/0016 20130101; B60W 2554/801 20200201;
G05D 1/0223 20130101; B60T 7/12 20130101; B60W 2554/804 20200201;
G08G 1/16 20130101; G05D 1/0088 20130101 |
International
Class: |
B60W 30/16 20060101
B60W030/16; G05D 1/02 20060101 G05D001/02; G05D 1/00 20060101
G05D001/00; B60W 30/14 20060101 B60W030/14; B60W 50/00 20060101
B60W050/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 17, 2016 |
JP |
2016-224532 |
Claims
1. A traveling control apparatus which is applied to a vehicle
including a target detecting unit configured to detect targets
existing ahead in a traveling direction of an own vehicle, and
which includes a target-following control unit configured to
recognize the target traveling ahead within an own lane which is a
traveling lane in which the own vehicle travels, as a target to be
followed, among the targets detected by the target detecting unit,
and perform a target-following control process on the target to be
followed, the traveling control apparatus comprising: a probability
calculating unit configured to calculate a probability that the
target to be followed is within the own lane; a determining unit
configured to determine whether a degree of recognition of the
target detecting unit with respect to the target to be followed
recognized by the target-following control unit is in a weakly
recognized state where the degree of recognition is weaker than a
predetermined degree; a reliability setting unit configured to set
a reliability of the target to be followed recognized by the
target-following control unit on a basis of the probability
calculated by the probability calculating unit and a determination
result by the determining unit; and an acceleration control unit
configured to control acceleration of the own vehicle so that a
jerk which is a differential value of the acceleration becomes
smaller as the reliability of the target to be followed set by the
reliability setting unit is lower during a period in which the
target-following control process is performed by the
target-following control unit.
2. The traveling control apparatus according to claim 1, wherein
the acceleration control unit controls the acceleration so that the
jerk becomes smaller as the reliability of the target to be
followed set by the reliability setting unit is lower on condition
that a distance between the own vehicle and the target to be
followed is longer than a predetermined distance.
3. The traveling control apparatus according to claim 1, wherein
the determining unit determines that a degree of recognition by the
target detecting unit of the target to be followed, recognized by
the target-following control unit, is in the weakly recognized
state during a period in which a predetermined time has elapsed
since the target to be followed recognized by the target-following
control unit was no longer detected by the target detecting
unit.
4. The traveling control apparatus according to claim 1, wherein:
the target detecting unit acquires information in which a parameter
for detecting the target and detects the target when the parameter
included in the information is greater than a first predetermined
value; and in a case where the parameter included in the
information acquired by the target detecting unit when the target
to be followed is detected is less than a second predetermined
value which is set at a value greater than the first predetermined
value, the determining unit determines that the degree of
recognition by the target-following control unit, of the target to
be followed detected by the target detecting unit, is in the weakly
recognized state.
5. The traveling control apparatus according to claim 1, wherein
the reliability setting unit sets the reliability at a first
reliability in a case where the probability calculated by the
probability calculating unit is greater than a first threshold,
sets the reliability at a second reliability which is lower than
the first reliability in a case where the probability calculated by
the probability calculating unit is greater than a second threshold
which is set at a value smaller than the first threshold, and is
less than the first threshold, and, in addition, it is determined
by the determining unit that the degree of recognition by the
target detecting unit of the target to be followed is not in the
weakly recognized state, sets the reliability at a third
reliability which is lower than the second reliability in a case
where the probability calculated by the probability calculating
unit is greater than the second threshold and is less than the
first threshold, and, in addition, it is determined by the
determining unit that the degree of recognition by the target
detecting unit of the target to be followed is in the weakly
recognized state, sets the reliability at a fourth reliability
which is lower than the third reliability in a case where the
probability calculated by the probability calculating unit is less
than the second threshold, and, in addition, it is determined by
the determining unit that the degree of recognition by the target
detecting unit of the target to be followed is not in the weakly
recognized state, and sets the reliability at a fifth reliability
which is lower than the fourth reliability in a case where the
probability calculated by the probability calculating unit is less
than the second threshold, and, in addition, it is determined by
the determining unit that the degree of recognition by the target
detecting unit of the target to be followed is in the weakly
recognized state.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application is a continuation application of
International Application No. PCT/JP2017/039082, filed Oct. 30,
2017, which claims priority to Japanese Patent Application No.
2016-224532, filed Nov. 17, 2016. The contents of these
applications are incorporated herein by reference in their
entirety.
BACKGROUND
Technical Field
[0002] The present disclosure relates to a traveling control
apparatus which causes an own vehicle to travel while following a
preceding vehicle which travels ahead in a traveling direction of
the own vehicle.
Related Art
[0003] ACC (Adaptive Cruise Control) selects a preceding vehicle
among other vehicles existing around a vehicle, ahead in a
traveling direction of the vehicle, and causes the vehicle to
follow the preceding vehicle.
SUMMARY
[0004] The present disclosure provides a traveling control
apparatus. In the present disclosure, a traveling control apparatus
is applied to a vehicle including a target detecting unit
configured to detect targets existing ahead in a traveling
direction of an own vehicle. The traveling control apparatus
calculates a probability that the target to be followed is within
an own lane, and determines whether a degree of recognition by the
target detecting unit of the target to be followed is in a weakly
recognized state where the degree of recognition is weaker than a
predetermined degree. The apparatus sets a reliability of the
target to be followed on the basis of the probability calculated by
a probability calculating process and a determination result by a
determining process, and controls acceleration of an own vehicle so
that a jerk which is a differential value of the acceleration
becomes smaller as the reliability of the target to be followed is
lower while the target-following control process is performed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] The above and other objects, features and advantages of the
present disclosure will become more clear from the following
detailed description with reference to the accompanying drawings,
in which:
[0006] FIG. 1 is a schematic configuration diagram of a traveling
control system according to the present embodiment;
[0007] FIG. 2 is a schematic diagram illustrating a situation where
a vehicle traveling in another lane is erroneously recognized as a
preceding vehicle which is traveling ahead within an own lane;
[0008] FIG. 3 is a flowchart of control to be performed by a
detection ECU according to the present embodiment; and
[0009] FIG. 4A and 4B are timing charts illustrating an aspect of
target acceleration control according to the present
embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0010] The inventor of the present disclosure has studied the
following technique as a traveling control apparatus capable of
suppressing fluctuation of acceleration of an own vehicle.
[0011] In the ACC, acceleration and deceleration control is
performed so that a distance between a vehicle and a preceding
vehicle becomes constant so as to cause the vehicle to follow the
selected preceding vehicle. Further, in the case where a preceding
vehicle does not exist, control of maintaining constant speed of
the vehicle is performed so that the speed of the vehicle becomes
speed set by a driver, a speed limit of a road, or the like.
[0012] By the way, for example, a case will be assumed where the
ACC is performed in a situation where the own vehicle is traveling
in an inner lane among two lanes, and another vehicle is traveling
in an outer lane. At this time, there is a possibility that, by the
other vehicle turning left in a situation where the other vehicle
is traveling ahead of the own vehicle, the other vehicle which
turns left ahead in the traveling direction of the own vehicle may
be captured. At this time, it is difficult for the own vehicle to
determine whether the other vehicle is traveling on the own lane,
and there is a possibility that the own vehicle may recognize the
other vehicle as a preceding vehicle and may perform unnecessary
deceleration. To address this, in Japanese Unexamined Patent
Application Publication No. 2015-58752 (hereinafter, referred to as
"JP-2015-58752-A"), an own lane existence probability is calculated
as a possibility that an object exists in the own lane on the basis
of a lateral location of the object existing ahead of the own
vehicle, and a limit value of target acceleration of the own
vehicle is set in accordance with the calculated own lane existence
probability. Meanwhile, the limit value of the target acceleration
is set in accordance with a distance from the own vehicle to the
object. Then, by a smaller value between the respectively set limit
values of the target acceleration being determined as the limit
value of the target acceleration, it is possible to suppress
precipitous acceleration and deceleration even when a preceding
vehicle is erroneously selected.
[0013] However, in JP-2015-58752-A, because a limit value of target
acceleration is set only in accordance with an own lane existence
probability of an object and a distance from an own vehicle to the
object, it is assumed that a slope of the target acceleration until
the acceleration is controlled to be the set limit value of the
target acceleration becomes great. That is, in process of the
acceleration of the own vehicle being controlled to be the set
limit value of the target acceleration, there is a possibility that
the acceleration of the own vehicle may fluctuate rapidly. Further,
in JP-2015-58752-A, while an object is detected using a millimeter
wave radar, the object detected using the millimeter wave radar
does not necessarily actually exist. That is, there is a case where
the millimeter wave radar may erroneously detect an object which
does not exist for some reason. Therefore, while, there is a
situation where, even if an object is detected by the millimeter
wave radar, it is inappropriate to perform the ACC on the object
detected by the millimeter wave radar, JP-2015-58752-A neither
discloses nor suggests control in which the above-described
situation is taken into account. Therefore, there is a possibility
that target-following control process may be performed on a target
which does not actually exist, and acceleration of the own vehicle
may fluctuate.
[0014] The present disclosure has been made to solve the
above-described problem, and a main object of the present
disclosure is to provide a traveling control apparatus which can
judge whether a target is appropriate as a target for
target-following control on the basis of a traveling state of a
target and a target recognized state, and, in the case where there
is a high possibility that the target is inappropriate as the
target for the target-following control, can suppress fluctuation
of acceleration of an own vehicle.
[0015] The present disclosure is a traveling control apparatus
which is applied to a vehicle including a target detecting unit
configured to detect targets existing ahead in a traveling
direction of an own vehicle, and which includes a target-following
control unit configured to recognize the target traveling ahead
within an own lane which is a traveling lane in which the own
vehicle travels, as a target to be followed, among the targets
detected by the target detecting unit, and perform a
target-following control process on the target to be followed, the
traveling control apparatus including, a probability calculating
unit configured to calculate a probability that the target to be
followed is within the own lane, a determining unit configured to
determine whether a degree of recognition of the target detecting
unit with respect to the target to be followed recognized by the
target-following control unit is in a weakly recognized state where
the degree of recognition is weaker than a predetermined degree, a
reliability setting unit configured to set a reliability of the
target to be followed recognized by the target-following control
unit on the basis of the probability calculated by the probability
calculating unit and a determination result by the determining
unit, and an acceleration control unit configured to control
acceleration of the own vehicle so that a jerk which is a
differential value of the acceleration becomes smaller as the
reliability of the target to be followed set by the reliability
setting unit is lower during a period in which the target-following
control process is performed by the target-following control
unit.
[0016] For example, a case will be assumed where the
target-following control process is performed in a situation where
an own vehicle is traveling in an inner lane among two lanes, and
another vehicle is traveling in an outer lane. In this case, there
is a possibility that, by the other vehicle turning left in a
situation where the other vehicle travels ahead of the own vehicle,
the other vehicle which turns left ahead in the traveling direction
of the own vehicle may be captured. At this time, it is difficult
for the own vehicle to determine whether the other vehicle is
traveling on an own lane, and there is a possibility that the own
vehicle may erroneously recognize the other vehicle as a preceding
vehicle and may perform unnecessary deceleration.
[0017] To address this, at the present traveling control apparatus,
a probability that the target to be followed recognized by the
target-following control unit is within the own lane is calculated
by the probability calculating unit. Further, whether a degree of
recognition of the target detecting unit with respect to the target
to be followed is in the weakly recognized state is determined by
the determining unit while taking into account that the target
detected by the target detecting unit does not necessarily exist.
Then, a reliability of the target to be followed recognized by the
target-following control unit is set by the reliability setting
unit on the basis of the probability calculated by the probability
calculating unit and a determination result by the determining
unit. That is, whether the target to be followed recognized by the
target-following control unit is truly appropriate as a target for
target-following control is quantified as the reliability on the
basis of the probability calculated by the probability calculating
unit and the determination result by the determining unit.
Therefore, in the case where the reliability of the target to be
followed is set lower by the reliability setting unit, there is a
possibility that the target to be followed recognized by the
target-following control unit does not exist within the own lane or
there is a possibility that the target detected by the target
detecting unit does not even exist. Therefore, in the case where
the reliability of the target to be followed is set lower by the
reliability setting unit, the target to be followed recognized by
the target-following control unit is highly likely to be a target
which is not appropriate for a target for target-following
control.
[0018] Therefore, the acceleration of the own vehicle is controlled
so that the jerk becomes smaller as the reliability of the target
to be followed set by the reliability setting unit is lower. By
this means, it is possible to keep fluctuation of the acceleration
of the own vehicle smaller as a possibility that the target which
is not appropriate as a target for target-following control is
erroneously recognized as the target to be followed is higher.
[0019] The foregoing and other features and advantages of the
present disclosure will become more apparent in the light of the
following detailed description of preferred embodiments thereof as
discussed and illustrated in the accompanying drawings.
[0020] A traveling control system 100 to be applied to a vehicle
which travels by a drive wheel 20 being rotationally driven will be
described with reference to FIG. 1. The traveling control system
100 includes a detection ECU 10, a radar apparatus 12 and an
electric power steering 13.
[0021] The radar apparatus 12, which is, for example, a publicly
known millimeter wave radar which uses a high frequency signal of a
millimeter wave band as a transmission wave, is provided at a front
end portion of an own vehicle, has a region within a predetermined
detection angle as a detection range in which a target can be
detected, and detects a location of a target within the detection
range. Specifically, search waves are transmitted with a
predetermined period, reflected waves are received with a plurality
of antennas, and, in the case where intensity of the received
reflected waves (corresponding to a parameter for detecting a
target) is higher than first predetermined intensity (corresponding
to a first predetermined value), it is determined that a target
exists ahead in a traveling direction of the own vehicle, and a
distance to the target is calculated from transmission time of the
search waves and reception time of the reflected waves. Further,
relative speed (specifically, relative speed of a vehicle in a
traveling direction) is calculated from a frequency of the
reflected waves reflected by the target, which is changed by the
Doppler effect. In addition, azimuth of the target is calculated
from a phase difference among the reflected waves received with the
plurality of antennas. Note that, if the location and the azimuth
of the target can be calculated, it is possible to specify a
lateral location of the target which indicates a location with
respect to the own vehicle in a lateral direction which is
orthogonal to the traveling direction of the own vehicle.
Therefore, the radar apparatus 12 corresponds to a target detecting
unit. The radar apparatus 12 performs transmission of search waves,
reception of reflected waves, and calculation of a reflection
location and relative speed for each predetermined period, and
transmits the calculated reflection location and relative speed to
the detection ECU 10.
[0022] The radar apparatus 12 is connected to the detection ECU 10.
The detection ECU 10, which is a computer including a CPU, a RAM, a
ROM, an I/O, or the like, implements various functions by the CPU
implementing a program installed in the ROM. Therefore, the
detection. ECU corresponds to a probability calculating unit, a
determining unit, a reliability setting unit, an acceleration
control unit and a target-following control unit.
[0023] In the present embodiment, the program installed in the ROM
is a control program for capturing a preceding vehicle which
travels ahead within an own lane which is a traveling lane in which
the own vehicle travels, on the basis of information (such as the
calculated location and relative speed) of the target detected by
the radar apparatus 12 and causing specified target-following
control process to be performed while the preceding vehicle is
captured. Note that, in the case where a preceding vehicle is not
captured, traveling control in which traveling is performed at set
predetermined vehicle speed is performed.
[0024] In the present control program, an own lane existence
probability which is a probability that the target is within the
own lane is calculated on the basis of a lateral location of the
target which exists ahead of the own vehicle, and which is detected
by the radar apparatus 12, with respect to the own vehicle. A
greater own lane existence probability is calculated for a smaller
lateral location of the target. A target for which the calculated
own lane existence probability is higher than a predetermined
probability (for example, set at 50%) is determined as a preceding
vehicle which travels ahead within the own lane, and the preceding
vehicle is recognized as a target to be followed. Then, target
acceleration is set so that a distance between the own vehicle and
the target to be followed is maintained at a target distance
between vehicles. Note that the target distance between vehicles
changes in accordance with vehicle speed of the own vehicle.
Further, the distance between the own vehicle and the target to be
followed is acquired from the radar apparatus 12.
[0025] Steering processing of controlling the traveling direction
of the own vehicle is performed so as to cause the own vehicle to
travel while following the target to be followed while accelerating
and decelerating the own vehicle by transmitting a control command
to an engine and a brake apparatus which are not illustrated, on
the basis of the set target acceleration. Therefore, the electric
power steering 13 is provided at the own vehicle as an apparatus
which is driven by a steering command from the detection ECU
10.
[0026] The electric power steering 13 includes a steering 13b which
operates a steering angle of the drive wheel 20 provided at the
vehicle and a steering electric motor 13a. The steering electric
motor 13a generates steering force (torque) which assists operating
force of the steering 13b. As this torque is greater, the steering
angle of the drive wheel 20 becomes greater. Further, the steering
electric motor 13a generates steering force (torque) of operating
the steering 13b during target-following control.
[0027] For example, as illustrated in FIG. 2, a case will be
assumed where target-following control process is performed in a
situation where the own vehicle is traveling in an inner lane among
two lanes, and another vehicle is traveling in an outer lane. In
this case, there is a possibility that, by the other vehicle
turning left in a situation where the other vehicle is traveling
ahead of the own vehicle, the other vehicle which turns left ahead
in the traveling direction of the own vehicle may be captured. In
this event, as illustrated in FIG. 4A, there is a case where the
own vehicle erroneously recognizes the other vehicle as the target
to be followed as a result of the own lane existence probability of
the other vehicle becoming higher than the predetermined
probability as the lateral location of the other vehicle becomes
smaller. At this time, the relative speed of the own vehicle with
respect to the other vehicle in the traveling direction of the own
vehicle tends to be higher. In addition, in the case where the
distance between the own vehicle and the target to be followed
becomes shorter than the target distance between vehicles, as
indicated with a dotted line in a bottom portion of FIG. 4A, there
is a possibility that the own vehicle is unnecessarily decelerated
as a result of the target acceleration being set at a negative
value.
[0028] To address this, to determine whether the target to be
followed truly is within the own lane, a first threshold, and a
second threshold which is set at a value smaller than the first
threshold and greater than the predetermined probability are
provided separately from the predetermined probability. By this
means, in the case where the own lane existence probability of the
target is greater than the first threshold, it can be determined
that a probability that the target to be followed is within the own
lane is the highest. Further, in the case where the own lane
existence probability of the target to be followed is greater than
the second threshold and smaller than the first threshold, while
the probability that the target to be followed is within the own
lane is lower than that in the case where the own lane existence
probability of the target to be followed is greater than the first
threshold, it can be determined that the target to be followed
substantially is within the own lane. In the case where the own
lane existence probability of the target to be followed is smaller
than the second threshold and greater than the predetermined
probability, it can be determined that a state is an unclear state
where, while the target to be followed may exist within the own
lane, there is also a possibility that the target to be followed
does not exist within the own lane.
[0029] By the way, while, in the present embodiment, a target is
detected using the radar apparatus 12, even in the case where a
target continuously exists, the target does not necessarily
continue to be detected by the radar apparatus 12, and there is a
case where the target cannot be detected in a certain detection
cycle. In this case, it is difficult to determine whether the
target actually disappears or the target has failed to be detected.
Therefore, in the case where the target cannot be detected in a
certain detection cycle, until predetermined time has elapsed since
then, processing of continuously detecting the target assuming that
the target exists has been conventionally performed. Then, in the
case where the target cannot be detected after the predetermined
time has elapsed, detection of the target is finished assuming that
the target disappears. Given that such processing is performed,
during a period in which the predetermined time has elapsed since
the target recognized as the target to be followed was no longer
detected by the radar apparatus 12, it is determined that a degree
of recognition of the radar apparatus 12 with respect to the target
to be followed is in a weakly recognized state where the degree of
recognition is weaker than a predetermined degree.
[0030] The detection ECU 10 sets the reliability of the target to
be followed on the basis of the calculated own lane existence
probability and a determination result as to whether the degree of
recognition of the radar apparatus 12 with respect to the target to
be followed is in the weakly recognized state. In other words,
whether the recognized target to be followed is truly appropriate
as a target for target-following control is quantified as the
reliability on the basis of the calculated own lane existence
probability and the determination result as to whether the degree
of recognition of the radar apparatus 12 with respect to the target
to be followed is in the weakly recognized state.
[0031] As the own lane existence probability of the target to be
followed is smaller, the target to be followed is less likely to
exist within the own lane. If the target to be followed is not
traveling within the own lane, because it can be considered that
the target recognized as the target to be followed is inappropriate
as a target for target-following control, the reliability of the
target to be followed is set lower as the own lane existence
probability of the target to be followed is smaller.
[0032] Further, in the case where the degree of recognition of the
radar apparatus 12 with respect to the target to be followed is in
the weakly recognized state, there is a possibility that the target
recognized as the target to be followed does not even exist. Also
in this case, because there is a possibility that the target
recognized as the target to be followed is inappropriate as the
target for target-following control, in the case where it is
determined that the degree of recognition of the radar apparatus 12
with respect to the target to be followed is in the weakly
recognized state, the reliability of the target to be followed is
set lower than in a case where it is not determined that the degree
of recognition of the radar apparatus 12 with respect to the target
to be followed is in the weakly recognized state. The method for
setting the reliability of the target to be followed will be
described in more detail later.
[0033] The detection ECU 10 controls the acceleration of the own
vehicle so that a temporal rate of change of the acceleration
becomes smaller as the reliability set for the target recognized as
the target to be followed is lower. More specifically, the target
acceleration is set so that a jerk which is a value obtained by
performing differentiation on the acceleration (differential value
of the acceleration) becomes smaller as the reliability set for the
target recognized as the target to be followed is lower.
[0034] The method for setting the reliability of the target to be
followed will be described in more detail. In the case where the
own lane existence probability of the target to be followed is
smaller than the above-described predetermined probability, the
reliability is not set in the first place assuming that a preceding
vehicle traveling ahead within the own lane does not exist. In the
case where the own lane existence probability of the target to be
followed is greater than the predetermined probability and smaller
than the second threshold, and, in addition, it is determined that
the degree of recognition of the radar apparatus 12 with respect to
the target to be followed is in the weakly recognized sate, the
reliability of the target to be followed is set at a fifth
reliability which is the lowest. In the case where the own lane
existence probability of the target to be followed is greater than
the predetermined probability and smaller than the second
threshold, and, in addition, it is determined that the degree of
recognition of the radar apparatus 12 with respect to the target to
be followed is not in the weakly recognized state, the reliability
of the target to be followed is set at a fourth reliability which
is higher than the fifth reliability.
[0035] In the case where the own lane existence probability of the
target to be followed is greater than the second threshold and
smaller than the first threshold, and, in addition, it is
determined that the degree of recognition of the radar apparatus 12
with respect to the target to be followed is in the weakly
recognized state, the reliability of the target to be followed is
set at a third reliability which is higher than the fourth
reliability. In the case where the own lane existence probability
of the target to be followed is greater than the second threshold
and smaller than the first threshold, and, in addition, it is
determined that the degree of recognition of the radar apparatus 12
with respect to the target to be followed is not in the weakly
recognized state, the reliability of the target to be followed is
set at a second reliability which is higher than the third
reliability.
[0036] In the case where the own lane existence probability of the
target to be followed is higher than the first threshold, the
reliability is set at a first reliability which is higher than the
second reliability (which is the highest) regardless of a
determination result as to whether the degree of recognition of the
radar apparatus 12 with respect to the target to be followed is in
the weakly recognized state. In the case where the own lane
existence probability of the target to be followed is higher than e
first threshold, the target to be followed is most likely to exist
within the own lane. In this situation, a case will be assumed
where the reliability of the target to be followed is set lower
than in a case where it is not determined that the degree of
recognition of the radar apparatus 12 with respect to the target to
be followed is in the weakly recognized state, because it is
determined that the degree of recognition of the radar apparatus 12
with respect to the target to be followed is in the weakly
recognized state. In this case, if target acceleration control
which will be described later is performed in accordance with the
set reliability, because the target acceleration of the own vehicle
is controlled so that the jerk becomes smaller than that in a case
where the reliability is higher, a possibility of collision with
the target to be followed increases in the case where the target to
be followed exists. Therefore, in the case where the own lane
existence probability of the target to be followed is higher than
the first threshold, the reliability is set at the first
reliability which is the highest reliability regardless of the
determination result of the degree of recognition of the radar
apparatus 12 with respect to the target to be followed. By this
means, in the case where the target to be followed is within the
own lane, even if the degree of recognition of the radar apparatus
12 with respect to the target to be followed is in the weakly
recognized state, target-following control assuming that the target
to be followed exists can be performed, so that it is possible to
increase safety of target-following traveling.
[0037] The target acceleration is specifically set as follows in
accordance with the reliability of the target to be followed set
using the above-described method. For example, in the case where
target-following control process is performed on the target to be
followed for which the first reliability is set, the target
acceleration is set in a similar manner to that set conventionally.
Meanwhile, in the case where target-following control process is
performed on the target to be followed for which the second
reliability is set, the target acceleration is controlled so that
the jerk becomes smaller than that in a case where target-following
control process is performed on the target to be followed for which
the first reliability is set. In this manner, because the target
acceleration is controlled so that the jerk becomes smaller as the
reliability of the target to be followed is lower, in the present
embodiment, in the case where target-following control process is
performed on the target to be followed for which the fifth
reliability which is the lowest reliability is set, the target
acceleration is controlled so that the jerk becomes the
smallest.
[0038] In the present embodiment, target acceleration control
illustrated in FIG. 3 which will be described later is performed by
the detection ECU 10. The target acceleration control illustrated
in FIG. 3 is repeatedly performed with a predetermined period by
the detection ECU 10 while the detection ECU 10 is powered on.
[0039] First, in step S100, it is determined whether a target is
detected by the radar apparatus 12 In the case where a
determination result of the determination processing in step S100
is Yes, the processing proceeds to step S110, and an own lane
existence probability of the target detected by the radar apparatus
12 is calculated.
[0040] In step S120, it is determined whether the own lane
existence probability of the target calculated in step S110 is
smaller than the above-described predetermined probability. In the
case where a determination result of the determination processing
in step S120 is No, the processing proceeds to step S130, and the
detected target is recognized as the target to be followed.
[0041] In step S140, it is determined whether the own lane
existence probability of the target to be followed is smaller than
the second threshold. In the case where a determination result of
the determination processing in step S140 is Yes (S140: Yes), the
processing proceeds to step S150.
[0042] In step S150, it is determined whether the degree of
recognition of the radar apparatus 12 with respect to the target to
be followed is in the weakly recognized state by determining
whether it is during a period in which the predetermined time has
elapsed since the target recognized as the target to be followed
was no longer detected by the radar apparatus 12. In the case where
a determination result of the determination processing in step S150
is No, the processing proceeds to step S160, and the reliability of
the target to be followed is set at the fourth reliability. Then,
the processing proceeds to step S170. In the case where a
determination result of the determination processing in step S150
is Yes, the processing proceeds to step S190, and the reliability
of the target to be followed is set at the fifth reliability. Then,
the processing proceeds to step S170.
[0043] In the case where a determination result of the
determination processing in step S140 is No, the processing
proceeds to step S200. In step S200, it is determined whether the
own lane existence probability of the target to be followed is
smaller than the first threshold (the first threshold>the second
threshold>the predetermined probability). In the case where a
determination result of the determination processing in step S200
is Yes, the processing proceeds to step S210.
[0044] In step S210, it is determined whether the degree of
recognition of the radar apparatus 12 with respect to the target to
be followed is in the weakly recognized state by determining
whether it is during a period in which the predetermined time has
elapsed since the target recognized as the target to be followed
was no longer detected by the radar apparatus 12. In the case where
a determination result of the determination processing in step S210
is Yes, the processing proceeds to step S220, and the reliability
of the target to be followed is set at the third reliability. Then,
the processing proceeds to step S170. In the case where a
determination result of the determination processing in step S210
is No, the processing proceeds to step S230, and the reliability of
the target to be followed is set at the second reliability. Then,
the processing proceeds to step S170.
[0045] In the case where a determination result of the
determination processing in step S200 is No, the processing
proceeds to step S240, and the reliability of the target to be
followed is set at the first reliability. Then, the processing
proceeds to step S170.
[0046] In step S170, the target acceleration is set while the jerk
is restricted in accordance with the reliability set in one of step
S160, step S190, step S220, step S230 and step S240. Then, in step
S180, target-following control process is performed so that the own
vehicle travels while following the target to be followed while
accelerating and decelerating the own vehicle by transmitting a
control command to the engine and the brake apparatus on the basis
of the target acceleration set in step S170. Then, the present
control is finished.
[0047] In the case where a determination result of the
determination processing in step S100 is No, or in the case where a
determination result of the determination processing in step S120
is Yes, the present control is finished.
[0048] An aspect of the target acceleration control according to
the present embodiment will be described next with reference to
FIG. 4A and FIG. 4B. Note that, in both FIG. 4A and FIG. 4B, the
present control is indicated with solid lines, and conventional
control is indicated with dotted lines. Further, for the purpose of
explanation, it is assumed that, while the target-following control
process is performed on the target to be followed, it is determined
that the degree of recognition of the radar apparatus 12 with
respect to the target recognized as the target to be followed is in
the weakly recognized state.
[0049] In FIG. 4A and FIG. 4B, because a target for which the own
lane existence probability is greater than the predetermined
probability does not exist, in a situation where the target to be
followed is not captured, the target acceleration is set so that
the own vehicle travels at predetermined vehicle speed (see time t0
to t1). Then, in the case where a target for which the own lane
existence probability becomes greater and exceeds the predetermined
probability (50%) is detected, the target is recognized as the
target to be followed (see time t1). In FIG. 4A and FIG. 4B, a
situation is assumed where a distance between the target recognized
as the target to be followed and the own vehicle is shorter than
the target distance between vehicles. Therefore, the target
acceleration is controlled to be greater in a negative
direction.
[0050] In FIG. 4A, the own lane existence probability of the target
to be followed is calculated as being greater than the
predetermined probability and being smaller the second threshold.
Further, because it is assumed that it is determined that the
degree of recognition of the radar apparatus 12 with respect to the
target to be followed is in the weakly recognized state, the
reliability of the target to be followed is set at the fifth
reliability. In this case, the target acceleration is controlled so
that the jerk becomes smaller compared to that in the conventional
control. Then, in the case where it is determined that the own lane
existence probability of the target to be followed becomes smaller
than the predetermined probability, target-following control
performed on the target recognized as the target to be followed is
cancelled, and the target acceleration control is also cancelled in
accordance with this cancelation (see time t2). Then, the target
acceleration is set so that the own vehicle travels at
predetermined vehicle speed assuming that the target to be followed
is not captured.
[0051] In FIG. 4B, during a period in which the own lane existence
probability of the target to be followed is greater than the
predetermined probability and smaller the second threshold (see
time t1 to t12), the reliability of the target to be followed is
set at the fifth reliability while also taking into account that it
is determined that the degree of recognition of the radar apparatus
12 with respect to the target to be followed is in the weakly
recognized state. Therefore, the target acceleration is controlled
so that the jerk becomes smaller than that in the conventional
control in a similar manner to the target acceleration control
performed during time t1 to t2 in FIG. 4A. Then, in the case where
the own lane existence probability of the target to be followed
increases, and it is determined that the own lane existence
probability of the target to be followed becomes greater than the
second threshold and becomes smaller than the first threshold (see
time t12), the reliability of the target to be followed is set at
the third reliability while also taking into account that it is
determined that the degree of recognition of the radar apparatus 12
with respect to the target to be followed is in the weakly
recognized state. Therefore, the target acceleration is set so that
the jerk becomes greater than that in a case where the reliability
of the target to be followed is set at the fifth reliability.
[0052] In the case where the own lane existence probability of the
target to be followed decreases, and the own lane existence
probability of the target to be followed becomes greater than the
predetermined probability and smaller than the second threshold,
the reliability of the target to be followed is set at the fifth
reliability. In accordance with this, the target acceleration is
set so that the jerk becomes smaller than that in a case where the
reliability of the target to be followed is set at the third
reliability (see time t13). Then, in the case where it is
determined that the own lane existence probability of the target to
be followed becomes smaller than the predetermined probability, the
target-following control performed on the target recognized as the
target to be followed is cancelled, and the target acceleration
control is also cancelled in accordance with this cancellation (see
time t14). Then, assuming that a target to be followed is not being
captured, the target acceleration is set so that the own vehicle
travels at predetermined vehicle speed.
[0053] The present embodiment provides the following effects by the
above-described configuration.
[0054] It is possible to appropriately set the reliability of the
target to be followed on the basis of the own lane existence
probability of the target to be followed and a determination result
as to whether the degree of recognition of the radar apparatus 12
with respect to the target to be followed is in the weakly
recognized state. Further, the acceleration of the own vehicle is
controlled so that the jerk becomes smaller as the set reliability
of the target to be followed is lower. By this means, it is
possible to keep fluctuation of the acceleration of the own vehicle
smaller as a possibility that the target which is not appropriate
as the target for target-following control is erroneously
recognized as the target to be followed is higher.
[0055] It is determined that the degree of recognition of the radar
apparatus 12 with respect to the target to be followed is in the
weakly recognized state during a period in which the predetermined
time has elapsed since the target to be followed was no longer
detected by the radar apparatus 12. By this means, it is possible
to set the reliability of the target to be followed while taking
into account a situation where the target temporarily disappears
due to a failure to detect the target being followed.
[0056] The above-described embodiment can be also implemented while
changes are made as follows. For comparison, the following
configurations in other examples may be individually applied to the
configuration of the above-described embodiment, or arbitrary
combination may be applied to the configuration of the
above-described embodiment.
[0057] In the above-described embodiment, the radar apparatus 12
detects a target. Concerning this point, the apparatus does not
have to be limited to the radar apparatus 12, and, for example, an
imaging apparatus may detect an object. The imaging apparatus
includes a monocular camera using, for example, a CCD camera, a
CMOS image sensor, a near-infrared camera, or the like, a stereo
camera, or the like. In this case, if it is possible to detect
white lines which separate the own lane on the basis of an image
captured by the imaging apparatus, it is possible to determine
whether the target is within the own lane more accurately. As a
result, it is possible to set more accurate reliability for the
target to be followed.
[0058] In the above-described embodiment, the target acceleration
is controlled so that the jerk becomes smaller in accordance with
the reliability of the target to be followed regardless of the
distance between the own vehicle and the target to be followed.
Concerning this point, it is also possible to perform processing of
controlling the target acceleration so that the jerk becomes
smaller in accordance with the reliability of the target to be
followed on condition that the distance between the own vehicle and
the target to be followed is longer than a predetermined distance.
Note that, in the present another example, while the predetermined
distance is set at a distance equal to the target distance between
vehicles, the predetermined distance may be set longer or shorter
than the target distance between vehicles.
[0059] Accuracy of target detection by the radar apparatus 12
degrades as the distance between the own vehicle and the target to
be followed is longer. Further, as the distance between the own
vehicle and the target to be followed is longer, it becomes more
difficult to accurately detect a lateral location of the target to
be followed, which results in occurrence of an error in the own
lane existence probability of the target to be followed. Therefore,
the target is more likely to be erroneously recognized as the
target to be followed although the target is not traveling in the
own lane. That is, it can be assumed that, as the distance between
the own vehicle and the target to be followed is longer, the
reliability of the target to be followed degrades. Therefore, in
the case where the distance between the own vehicle and the target
to be followed is longer than the predetermined distance, it is
preferable to perform the present control.
[0060] Meanwhile, in the case where the distance between the own
vehicle and the target to be followed is shorter than the
predetermined distance, if the target acceleration is controlled so
that the jerk becomes smaller because the reliability of the target
to be followed is low, the own vehicle cannot be sufficiently
decelerated even if the target to be followed exists, and there is
a possibility that the own vehicle may collide with the target to
be followed. Therefore, in the case where the distance between the
own vehicle and the target to be followed is shorter than the
predetermined distance, the acceleration can be controlled as
appropriate so that the jerk becomes greater in accordance with the
distance between the own vehicle and the target to be followed by
performing conventional target-following control process without
performing the present control process, so that it is possible to
improve safety of target-following traveling.
[0061] While, in the above-described embodiment, a target is
detected using the radar apparatus 12, an object detected by the
radar apparatus 12 does not necessarily actually exist. That is,
there is a case where the radar apparatus 12 may erroneously detect
that an object exists for some reason even if a target does not
exist. Therefore, even if an object is detected by the radar
apparatus 12, there exists a situation where it is inappropriate to
perform a target-following control process on the target detected
by the radar apparatus 12.
[0062] It can be assumed that intensity of reflected waves received
by the antenna in the case where the target is erroneously detected
is smaller than intensity of reflected waves received by the
antenna in the case where the target is normally detected even if
the intensity is greater than a first predetermined intensity set
for detecting a target. Therefore, a second predetermined intensity
(second predetermined value) greater than the first predetermined
intensity may be provided in addition to the first predetermined
intensity, and, in the case where it is determined that the
intensity of the reflected waves is greater than the first
predetermined intensity and smaller than the second predetermined
intensity, it may be determined that the degree of recognition of
the radar apparatus 12 with respect to the target to be followed is
in the weakly recognized state assuming that there is a possibility
that the target may be erroneously detected. By this means, it is
possible to set the reliability of the target to be followed while
taking into account a possibility of erroneous detection of a
target.
[0063] Determination as to whether the intensity of the reflected
waves is greater than the first predetermined intensity and smaller
than the second predetermined intensity (hereinafter, referred to
as temporary flag determination) according to the present another
example may be performed in place of determination as to whether it
is during a period in which predetermined time has elapsed since
the target recognized as the target to be followed was no longer
detected by the radar apparatus 12 (hereinafter, referred to as
extrapolating state determination) described in the above-described
embodiment.
[0064] Alternatively, both the temporary flag determination and the
extrapolating state determination may be performed, and, in the
case where a positive determination result can be obtained from at
least one of the determination, it may be determined that the
degree of recognition of the radar apparatus 12 with respect to the
target to be followed is in the weakly recognized state.
Alternatively, reliability may be determined for each of the
extrapolating state determination and the temporary flag
determination. For example, the reliability of the target to be
followed may be set higher in the case where a positive
determination can be obtained in the extrapolating state
determination than in the case where a positive determination
result can be obtained in the temporary flag determination.
[0065] While the present disclosure has been described with
reference to the examples, the present disclosure is not limited to
the examples and structures. The present disclosure incorporates
various modified examples and modifications within an equivalent
range. In addition, various combinations, forms, and other
combinations and forms including only one element or more or fewer
elements fall within the scope and the scope of mind of the present
disclosure.
* * * * *